Frequency comb generation in a pulse-pumped normal dispersion Kerr mini-resonator

Area of Science:

• Nonlinear optics
• Photonics
• Optical frequency combs

Background:

• Kerr microresonators typically need dispersion perturbations for optical frequency comb generation in the normal dispersion regime.
• Existing methods often rely on complex structures like avoided mode crossings.

Purpose of the Study:

• To demonstrate that pulsed pump sources can initiate optical frequency comb formation in Kerr microresonators without dispersion perturbations.
• To show that pump-cavity desynchronization offers a tunable mechanism for comb properties.

Main Methods:

• Experimental demonstration using a fiber mini-resonator (6 cm radius).
• Driving the resonator with a pulsed pump source.
• Controlling the desynchronization between pump repetition rate and cavity free-spectral range (FSR).

Main Results:

• Achieved spectrally flat combs with 3 THz bandwidth, tunable over 2 THz.
• Generated combs with selectable line spacings from 0.54 GHz to 10.8 GHz by driving at FSR harmonics.
• Observed a novel form of Raman-assisted anomalous dispersion cavity soliton under large pump-cavity desynchronization.

Conclusions:

• Pulsed pumping offers a simplified route to optical frequency comb generation in Kerr microresonators.
• Pump-cavity desynchronization provides versatile tuning of comb center frequency and line spacing.
• The platform demonstrates significant flexibility and potential for new soliton physics.